Engines, pumps and motors

ABSTRACT

A fluid pump or motor has an inclined crankpin crankshaft drivably coupled to pistons slidable in cylinders having their axes parallel to the crankshaft axis. The cylinders are arranged around the crankshaft in first and second banks at opposite ends of the crankshaft. One cylinder bank has an inlet manifold chamber and the other an outlet manifold chamber. Each cylinder has an inlet and an outlet port, both controlled by valves. The appropriate port of each cylinder opens directly into the manifold chamber of the bank containing that cylinder while the other port of that cylinder is connected by a duct to the other manifold chamber which is formed in the other bank of cylinders.

United States Patent Bunyan Dec. 24, 1974 ENGINES, PUMPS AND MOTORS 1 Primary Examiner-William L. Freeh [76] Inventor. Thomas Walter Bunyan 5, Point I I Close,- Blackheath Lonzion SE 10, ttorngy, Agelrzt, 0 r Fzrm-Woodcock, Washburn, v England I urtz Mac ievvicz i 1 pp 2 A fluid pump or motor has an inclined crankpin crankshaft drivably coupled to pistons slidable in cyl- [30] Foreign Application priority Data inders having their axes parallel to the crankshaft axis. Jan 25 1972 Great Britain 3454/72 The cylinders are arranged around the crankshaft 1n first and second banks at opposite ends of the crankshaft. One cylinder bank has an inlet manifold cham- 9 1/4i;06l9blg5/(1)(2) I ber and the other an Outlet manifold chamber. Each I Fie'ld 480 502 cylinder has an inlet and an outlet port, both controlled by valves. The appropriate port of each cylinder opens directly into the manifold chamber of the [56] References Cited bank containing that cylinder while the other port of UNITED STATES PATENTS that cylinder is connected by a duct to the other mani- 2,8 44 Q Qg 7/1958 Pavesi 91/480 fold chamber which is formed in the other bank of cyl- 2,v09,422 5/1955 Bray 91/478 inders 3,057,545 10/1962 Ransom et al 417/264 3,370,510 Bunyan 74/60 11 Claims, 11 Drawing lgu es PATENTED DEC 2 41974 SHLIT 1 OF 8 mww Qw Pmlimeu mw 3,855.903

SHEET 2 [1F 8 sum 3 UF8 PATENTED DECM I974 This invention relates to fluid pumps and motors and internal combustionengines of the kind comprising a crank shaft having an inclined crank pin, a bearing sleeve in which the crank pin isrotatably received, first and second banks of cylinders at opposite ends of the crank pin, the cylinders in each bank being arranged around the crank shaft axis and facing the corresponding cylinders of the other bank with their axes parallel to the crank shaft axis, a set of piston rods each interconnecting a first piston in a cylinder of the-first bank with a second piston 'in the corresponding cylinder of the second bank and a rocker arm driving connection for each piston rod between the sleeve and the piston rod. Such a construction is shown for example in US. Pat. No. 3,370,510 as applied to an internal combustion engine.

The principle object of the present invention is to provide pumps, motors and engines of the kind defined above which are of compact construction having regard to their required performance while at the same time being of high efficiency, that is to say that fluid power losses within the pump, motor or engine are kept at a low value.

According to the present invention, there is provided I a fluid pump or motor or internal combustion engine of .the first bank are connected respectively to the first and second manifold chambers by ducts extending between the two banks.

With this arrangement, no additional external pipe connections are required between the various cylinders in each bank and between the two banks. The connection to the manifold chamber associated with one bank of cylinders forms say the inlet for the whole pump, motor or engine while the other connection forms the outlet or exhaust. There is thus obtained a very compact and simple construction having the important advantage that the fluid flow path through the pump, engine or motor is kept short and free from constrictions while in the case particularly of pumps and motors the number of changes of direction imposed on the fluid is small as compared with other designs of fluid pumps and motors.

Advantageously, particularly in fluid pumps and motors the corresponding valves of corresponding cylin d'ers of the two banks are interconnected by tie rods .extending through the said ducts. In this way, the same fluid pressure in a duct is applied to the two valves at opposite ends of the tie rod. The forces generated by the fluid pressure on the two'valves are thus balanced, thereby minimizing the force required to move the two valves and their tie rod between the open and closed positions of the two valves. 7

ln'the preferred embodiments particularly of fluid pumps and motors, the exteriors of the ducts form guideways for crossheads connected to the piston rods and to the rocker arms. Furthermore, the ducts are 2 formed in hollow tie bars interconnecting the two banks of cylinders and thus rigidly holding them at their correct spacing.

An embodiment of the invention together with some modifications thereof will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a view mainly in axial section but partly in elevation of a pump or motor according to the invention;

FIG. 2 is a cross section on the line -11 of FIG. 1;

FIG. 3 is a cross section on the line lIIIll of FIG. 1;

FIG. 4 is a section on the curved line lVlV of FIG.

FIG. 5 is a cross section on the line VV in FIG. 1;

FIG. 6 is an'exploded perspective view of the assemblyformed by one of the hollow tie bars and the two banks of cylinders; i

FIG. 7. is a fragmentary view in the direction of the arrow VII of FIG. 6;

FIG. 8 is a perspective view of the driving connection between a rocker arm and a piston rod;

FIG. 9 is a view corresponding to a portion of FIG. 4 of a modified form of valve operating gear;

FIG. 10 is an axial section through a modifi'ed valve control arrangement; and

FIG. 11 is an axial section of a fabricated crank shaft.

grally with the cylinder block 1 is a first fluid connection 3 while a second fluid connection 4 is formed integrally with the second cylinder block 2. One of the connections 3 and 4 serves as inlet and the otheras outlet for hydraulic liquid such as oil. The connection 3 communicates with an annular manifold chamber 5 in the first cylinder block 1 while the second fluid connection 4 communicates with the second annular manifold chamber 6 in the second cylinder block 2.

Mounted in bearings 7 in the inner walls of the annular chambers 5 and 6 are the journals 8 of a crank shaft 9 having an inclined crank pin 10. A split sleeve 11 consisting of two halves having flanges 12 secured together by bolts 13 is rotatably mounted on the inclined crank pin 10 and has end bearing cheeks l4 cooperating with thrust faces 15 on the crank shaft 9 to ensure axial location of the bearing sleeve 11 and to withstand any axial forces which may be exerted on it.

The split sleeve 11 has a cylindrical external bearing surface which is interrupted by the diametrically opposed flanges l2 and by a central annular thrust ring or flange of tapered section which is formed in two halves, one half being integral with each half of the split bearing sleeve 11.

Each cylinder block 1, 2, has six cylinder bores 16, each cylinder bore 16 of one block being alignedwith the corresponding cylinder bore of the other block. Each cylinder bore 16 contains a piston 17, the two 'piston 17 in a pair of correspondingcylinder boresbeing connected by piston rods 18 to a crosshead 19. The crosshead bearing pin 20 which in turn is formed with a transverse cylindrical bore receiving a pintle 21 carried at the radially outer end of a rocker arm 22 (FIG.

of the bearing sleeve 11.

1), the inner surface of which forms a palm 23 bearing on the cylindrical surface of the bearing sleeve '11 (FIG. 3). Each palm has a groove of tapered section to receive the thrust ring 90 (FIG. 1). As described in US. Pat. No. 3,370,5 l small gaps are left between adjacent palms 23 to permit slight relative angular movement about the axis of the inclined crank pin 10.

One opposed pair of rocker arms 22 have their palms 23 formed with grooves 24 to accommodate the bolted flanges 12 of the bearing sleeve 11 (FIG. 3). Accordingly, these two rocker arms are effectively solid with the bearing sleeve 11 while the other four rocker arms are capable of slight angular movement about theaxis The palms 23 are held in contact with the bearing sleeve 11 by end rings 25 which are secured to the ends of the sleeve 11 and bear against the ends of the palms 23 while permitting the four palms 23 which are not en gaged with the flanges 12 to carry out their angular movement relative to the bearing sleeve 11.

Each cylinder 16 at its end remote from the associated crosshead 19 opens into a valve chamber 27 around the entire periphery of the outer end of the cylinder 16 This arrangement provides a large flow-cross section for liquid to enter or leave the cylinder, this flow section being at leastas great as the crosssectional area of the cylinder 16. As shown in the top lefthand corner of FIG. 1, the head of the piston 17 can move into the chamber 27 so as to increase the length of the stroke without increasing the overall length of the pump or motor.

Eachchamber 27 is elongated in the circumferencial direction on each side of the cylinder 16 to include first and second valve-controlled ports 28 and 29. One of the ports 28, 29 serves for the admission of liquid into thevalve chamber 27 and. thence into the cylinder 16 while the other of these ports permits the liquid to leave from the cylinder '16 through the valve chamber 27 when the piston 17 is moving towards the chamber 27. The ports 28 and 29 are'formed by cylindrical bores in which their valve 30 and 31 are slidable. The first ports 28 of the first bank 1 of cylinders open directly into lobes 32 of the annular chamber 5 in the first bank while the second ports 29 of the second bank 2 of cylinv the lobes 33 of the second annular chamber 6 by ducts 35 extending from one cylinder bank to the other. Similarly, the first ports 28 of the second cylinder bank 2 are connected to the lobes 32 of the first annular chamber 5 by ducts 36 similar to the ducts 35.

The valves 30 and 31 are each in the form of a piston. Corresponding valves'of the two cylinder banks are interconnected by long hollow tie rods 37. The tie rods 37 extend through the respective ducts 35, 36 so that no sealing arrangements are required at any point along the length of the tie rods between the two opposed valves which they interconnect.

In the embodiment shown in the drawings, each cylinder bank is formed as a single casting. The end portions-35a, 36a, of each duct 35, 36 are formed in the cylinder bank castings while the central portions 35b, 36b, of the ducts areformed by hollow tie bars 38. Each end of each tie bar 38 is enlarged on two sides to form lugs 39. Each tie bar end is received in a recess 40 in respective cylinder bank casting, the end face 41 of the tie bar being held against .the corresponding face 42 of the recess 40 by tapered dowels 43. A groove 44 is formed in the face 42 around the opening of the duct portion 35a, 36a. Adjacent each face 42 are drilled two holes 45 which communicate with the groove 44', preferably by extending parallel to the two radial sides of the groove sufficiently close to the end face 42 to break into the bottom of the groove. During assembly of the pump or motor, the ends of the tie bars are fitted into their recesses, holes for the dowels 43 are drilled and reamed so as to lie half in the cylinder bank casting and half in the lugs 39, the dowels 43 are fitted into position, uncured nitrile or other elastomeric gasketforming material is pumped into the grooves 44 through the holes 45 until the grooves 44 are filled. Heat is then applied, for example by placing the motor or pump in a heating chamber, until the elastomeric material has set and cured. Shouldered bolts 45a carrying sleeves 45b of compressible material such as rubber introduced into the holes 45 and are then tightened 1 with ribbed nuts 45c'in such a manner as to casue the sleeves to expand in contact with the cured elastomeric material in the groove 44, thereby compressing the latter to a pressure which may be greater than the working pressure expected within the pump or motor. In this way, a highly reliable seal is formed around the junctions of the portions 35a, 36a, and 35b, 36b respectively. Two lateral external surfaces of the tie bars 38 are machined at 46 with orientations such that the ad jacent surfaces 46 of two adjacent tie bars 38 are parallel to each other and form between them a guide for one of the crossheads 19.

A cylindrical casing 48,-which may be formed in segments, surrounds the tie bars 38 and its inner surface forms a'further guide surface for corresponding the curved external surfaces 49 on the crossheads 19. The casing 48 may be secured tothe cylinder bank castings 1 and 2 by pins 50.

One form of valve operating gear is shown in FIGS 1, 4 and. 5. Referring -to- FIG. 4, each valve 30, 31 is fixed to a valve rod 51 which is a se aled sliding fit in a closure member 52. The two valverods 5 1 of the valves associated with a cylinder 16 are connected by links 53 to opposite ends of a lever 54 which is pivoted at its mid point 55 in a fulcrum block 56 secured to an end face of the cylinder bank. In this way, the valves 30 and 31 are connected to operate in anti-phase, that is to say that when one of the valves is fullyopen the other is in the fully closed position in its port.

Each shaft 55 carries a cam follower arm 57 (FIG. 5) which cooperates with an annular cam track 58 secured to the crank shaft (FIG. 1

In the modification of this arrangement shown in FIG. 9, the valves associated with any particular cylinder are operated directly by the piston of that cylinder acting at the end of its outward stroke on a tappet pin 61 which is slidable through thewall of the cylinder bank (or an insert therein). and bears at its outer end 62 against a nose 63 carried by the lever arm 54, .the line of action of the tappet pin 61 on the nose 63 being spaced from the axis of the pivot shaft 56' of the lever 54. It will be appreciated that the tappet'pin 61 shown in FIG. 9 can only move the lever arm 54' clockwise. Anti-clockwise movement of the lever arm 54' is effected by the tappet pin in the corresponding cylinder of the other bank. In the case of a reversible motor, the

nose portion 63 maybe formed on a separate member 65 which may be moved along the arm 54 until a further nose portion 66 cooperates with the outer end 67 of a second tappet pin 68. This movement, to reverse the motor, may be effected by an actuator 69 which is connected to an actuator plate 70 having a slot 71 which the pivot shaft 56 is engaged, the plate 70 having arcuate slots 72 receiving pins 73 on the member 65, the pins 73 being slidable in radial slots 74 in the lever 54. i

As shown in section in the case of the tappet pin 68, the tappet pins are preferably formed in two halves interconnected by a stack of belleville washers 75 capable of absorbing impact shocks.

The valves, 30, 31 may be hollow and thus of lightweight construction so as not to impose heavy inertial loads on the valve operating gear. The valve rod 51 at one end of each tie rod 37 may be urged in one direction by a spring (not shown) thereby in some case dispensing with the need for a valve operating lever at that end of the tie rod. Alternatively, there may be a cam track at each end of the crank shaft, one cam track serving to operate the inlet valves while the other serves to operate the outlet valve. In this case, each valve operating lever would be a single-armed'lever, the spring at the far end of each tie rod serving to keep the cam follower in contact with its cam track.

FIG. shows an arrangement for rendering any selected pair of opposed cylinders inoperative in order to cut down the displacementof the pump or motor. In the case of a pump, this would reduce the delivery rate of the pump and accordingly its power requirements whereas in the case of a motor, this could cause the motor speed to increase, given a constant delivery rate of liquid at sufficient pressure. A pair of opposed cylinders can be kept out of effective service by holding the high pressure valves associated with the cylinders in their closed position and their low pressure valves in the open position. For this purpose, a stepped annular piston 101 surrounds an enlargement 102 on the valve, rod 51" of the low pressure valve of a cylinder. Two such operating rods are shown in FIG. 10 belonging, for example, to adjacent cylinders. The lower valve rod 51'' is free to operate normally. The valve rod 51" shown in the upperpart'of the figure is prevented from normal operation since its stepped annular piston 101 has been forced to the right, for example by fluid pressure applied in the chamber 103 to the left of the piston 101. Where the inlet and outlet valves of each cylinder are interconnected by a rocker arm 54, this arrange ment will keep the high pressure valve closed. The same arrangement may be applied to the cylinders at the opposite end of the pump or motor. In order to enable both high pressure valves of-a corresponding pair of cylinders to be maintained closed simultaneously, it will be necessary to provide the tie rods between the valves at opposite ends of the pump or motor with a resilient link of sufficient stiffness to ensurenormal valve operation while permitting a reduction in length of the tie rod between the high pressure valves when the latter are to be maintained closed.

An arrangement may be provided for varying the timing of a-cam track relative to the crank shaft.

This arrangement mayalso beapplied to both ends of a motor or pump in which case the timing of the inlet and outlet valves of the cylinders may be separately controlled. This in turn enables the effective portion of the piston strokes to be varied from zero. to the full stroke of the pump or motor,-thereby giving a continu ously variable displacement.

While the crank shaft may be formed from an integral forging, it isv also possible to construct the crank shaft from two smaller forgings 121 and 122 (FIG. 11) each of which has a hollow. cylindrical portion 123 and 124 respectively forming two halves of the crank pin. The two crankpin portions interengage by means of a hirth serrated coupling comprising triangular dogs on each half, the dogs having an apex angle of say The outer surfaces of the two crank pin portions canbe accurately machined before assembly and the two halves of the crank pin are then held together by means of a Morgrip (Trade Mark) pre-tensioned bolt 125, the bolt 125 being hollow and pre-tensioned by means of a rod (not shown) in the interior of the bolt acting between the closed end of the bolt interior and a hydraulic jack (not shown) at the other end of the bolt. During assembly, the jack is operated to pre-tension the bolt, the latter is inserted into the two crank pin portions 124 and 123 nuts 126 are engaged on the two ends of the bolt and tightened and the hydraulic jack and pre-stressing rod removed.

In order to assist in dynamically balancing the pump, engine or motor, balance weights 80 are secured to the crank shaft by bolts 81. By making thecrossheads l9 and piston rods 18 of light alloy, preferably of integral construction, the reciprocating masses can be considerably reduced thereby enabling the mass and size, of the balance weights to be reduced. Furthermore, the alloy chosen may be such as to have good wearing properties in relation to the guide surfaces 46 on the ducts 38 and also in relation to' the cross pins 20. The piston heads may then be detachable from the piston rods.

In the case of internal combustion engines, some of the ducts extending from one cylinder bank to the other will be conveying high temperature exhaust gases. It may-accordingly be undesirable for these ducts to act as tie bars 'or to enclose the tie rods'between the valves of the two cylinder banks. Similarly, it maybe preferable to guide the crossheads 19 on separate guides. Nevertheless, the three inlet ducts may be of the construction shown for the ducts 38, with the inlet valve tie rods extending through them.

I claim:

1. In a fluid pump or motor or internal combustion engine of the kind comprising a crank shaft having an inclined working portion, first and second banks of cylinders at opposite ends of the crank shaft working portion, the cylinders in each bank being arranged around the crank shaft axis and facing the corresponding cylinders of the other bank with their axes parallel to the crank shaft axis, a set of piston rods each interconnecting a first piston in a cylinder of the first bank with a second piston in the corresponding cylinder of the second bank and a driving connection for each piston rod, the improvements which comprise:

a first fluid connection, a first manifold chamber positionally associated with the first cylinder bank and serving both cylinder banks, said first fluid connection opening into said first manifold chamber, a second fluid connection, a second manifold chamber positionally associated with the second fluid connection opening into said second manifold chamber,

first and second valve-controlled ports for each cylinder of each bank,

the first ports. of the first cylinder bank opening into said first manifold chamber,

the second ports of the second cylinder bank opening into the second manifold chamber, first and second duct means extending between said first and second cylinder banks, I

said first duct means interconnecting the second valve ports of said first cylinder bank with said second manifold chamber, and

said second duct means interconnecting said first valve ports of said second cylinder bank with said first manifold chamber.

2. A pump, motor or engine according to claim 1, wherein the corresponding valves of corresponding cyl inders of the two banks-are interconnected by tie rods extending through the said ducts.

3. A pump, motor or engine according to claim 1, wherein the piston rods are drivably connected to their respective rocker arms through crossheads which are slidably guided on the exteriors of the ducts.

4. A pump or motor according to claim 1 wherein the two valves for each cylinder are interconnected for operation in antiphase.

5. A pump or'motor according to claim 4, wherein the valves are operated by tappet pins engaged by the headsof the pistons.

6. A pump, motor or internal combustion engine according to claim 1, wherein the valves are operated by a cam followers engaged with at least one cam track rotatable with the crankshaft.

7. A pump, motor or internal combustion engine according to claim 6, wherein the cam tracks are angularly adjustable relative to the crankshaft during rota tion of the crankshaft.

8. A pump, motor or engine according to claim 1, wherein the ducts'are formed in hollow tic bars interconnecting the two banks of cylinders.

9. A pump, motor or engine according to claim 8, wherein the hollowtie bars have enlargements at their ends received in recesses in the cylinder banks with tapered dowels inserted in tapered bores bounded partly by the enlargements and partly by the recess walls.

10. A pump or motor according to claim 9, wherein the end faces of the hollow tie bars are sealed to the mating faces of the cylinder banks by means of a gasket of elastomeric material located in a groove in one or both of the interfaces, and the gasket is mechanically precompressed.

11. A pump or motor according to claim 10, wherein the gasket is precompressed by means of a bolt carrying a sleeve of elastomeric material in contact with the gasket and located in a bore confining the sleeve to compress-the gasket when the bolt is tightened. 

1. In a fluid pump or motor or internal combustion engine of the kind comprising a crank shaft having an inclined working portion, first and second banks of cylinders at opposite ends of the crank shaft working portion, the cylinders in each bank being arranged around the crank shaft axis and facing the corresponding cylinders of the other bank with their axes parallel to the crank shaft axis, a set of piston rods each interconnecting a first piston in a cylinder of the first bank with a second piston in the corresponding cylinder of the second bank and a driving connection for each piston rod, the improvements which comprise: a first fluid connection, a first manifold chamber positionally associated with the first cylinder bank and serving both cylinder banks, said first fluid connection opening into said first manifold chamber, a second fluid connection, a second manifold chamber positionally associated with the second fluid connection opening into said second manifold chamber, first and second valve-controlled ports for each cylinder of each bank, the first ports of the first cylinder bank opening into said first manifold chamber, the second ports of the second cylinder bank opening into the second manifold chamber, first and second duct means extending between said first and second cylinder banks, said first duct means interconnecting the second valve ports of said first cylinder bank with said second manifold chamber, and said second duct means interconnecting said first valve ports of said second cylinder bank with said first manifold chamber.
 2. A pump, motor or engine according to claim 1, wherein the corresponding valves of corresponding cylinders of the two banks are interconnected by tie rods extending through the said ducts.
 3. A pump, motor or engine according to claim 1, wherein the piston rods are drivably connected to their respective rocker arms through crossheads which are slidably guided on the exteriors of the ducts.
 4. A pump or motor according to claim 1 wherein the two valves for each cylinder are interconnected for operation in antiphase.
 5. A pump or motor according to claim 4, wherein the valves are operated by tappet pins engaged by the heads of the pistons.
 6. A pump, motor or internal combustion engine according to claim 1, wherein the valves are operated by a cam followers engaged with at least one cam track rotatable with the crankshaft.
 7. A pump, motor or internal combustion engine according to claim 6, wherein the cam tracks are angularly adjustable relative to the crankshaft during rotation of the crankshaft.
 8. A pump, motor or engine according to claim 1, wherein the ducts are formed in hollow tie bars interconnecting the two banks of cylinders.
 9. A pump, motor or engine according to claim 8, wherein the hollow tie bars have enlargements at their ends received in recesses in the cylinder banks with tapered dowels inserted in tapered bores bounded partly by the enlargements and partly by the recess walls.
 10. A pump or motor according to claim 9, wherein the end faces of the hollow tie bars are sealed to the mating faces of the cylinder banks by means of a gaskEt of elastomeric material located in a groove in one or both of the interfaces, and the gasket is mechanically precompressed.
 11. A pump or motor according to claim 10, wherein the gasket is precompressed by means of a bolt carrying a sleeve of elastomeric material in contact with the gasket and located in a bore confining the sleeve to compress the gasket when the bolt is tightened. 